Oscillatory apparatus



p 1943. s. D. LAVOIE 2,328,561

OSCILLATORY APPARATUS Filed Aug. 5, 1941 3 Sheets-Sheet l INVENTOR Stephen lllmwoze IBMJZM ATTORNEY- 4 Patented Sept. 7, 1943 UNITED STATES PATENT OFFICE (01. 250-36) (Granted under the act of March 3, 1883, as

12 Claims.

amended April 30, 1928; 370

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to high frequency oscillatory circuits and devices, and more particularly to methods and apparatus for the utilization of such circuits and devices in oscillation generators, especially for the purpose of producing oscillations having a high degree of frequency stability.

The methods and apparatus of this invention are particularly useful for operations in what are today termed the ultra-high frequency or "micro-wave spectrums; for example, the range of frequencies above 50 vmegacycles per second; although it should be clearly understood that the utility of the invention is not limited to such frequencies.

One of the problems frequently encountered in high frequency electrical work is that of providing a high degree of frequency stability in apparatus such as oscillation generators, frequency determining resonance circuits, etc., and

also of providing such apparatus with means for readily changing the operating frequency while maintaining high frequency stability. In operations on lower frequencies good frequency stability may be obtained by use of piezo-electric crystals, but for high frequency operation the use of such crystals is impractical because of the impracticability of producing a crystal having the extremely small dimensions which would be .required. Of course, a crystalof practical dimensions can be used with harmonic generator or multi-vibrator apparatus, but such an arrangement is complicated, expensive, and bulky. Furthermore, even if some type of simple crystal control were practical, such apparatus does not permit easy variation of the operating frequency.

In accordance with my invention, by making the frequency determining portion of high frequency apparatus, such as an oscillation generator, for example, in the form of a heavy, mechanically rugged metal structure or housing having metal projections extending inwardly from opposite walls to form a lumped capacity element-and so dimensioned as to have a natural electrical resonance frequency equal to the desired operating frequency of the apparatus, I provide a structure which forms a high-Q resonsnce circuit of extremely high inherent frequency stability readily comparable to that obtainable with a piezo-electric crystal. Further, in accordance with my invention, means'areprovided to vary the relative positions of the internal projections so that the resonance frequency of the unit can be varied as desired. In oscillation generators embodying my invention, the oscillation generating elements are mounted inside of such a frequency determining unit so as to .be suitably coupled to it, thus completely shielding the entire generator apparatus and eliminating all possibility of parasitic coupling with external circuit elements, shieids, etc., which would detrimentally aifect its efficiency and cperatingstability.

Accordingly, it is an object of this invention to provide high frequency apparatus of extreme frequency stability, and to provide means whereby the operating frequency ofsuch apparatus may be easily adjusted throughout a-relatively wide range.

It is a further object of this invention to .provide such apparatus which is substantially seli"- contained and self-shielding, and which is simple, compact, and rugged, thereby being especially suitable for portable operation, as, for example, in aircraft-or other mobile equipment.

Other objects will be in ,part obvious and in part pointedout hereinafter.

For further disclosure of the invention, reference may be had to the followingdescription and to the accompanying drawings, showing oneembodiment of the invention selected merely for purposes of illustration, in which:

Figure 1-is ahorizontal section, taken on lines Il of Figure 2, of an ultra-high frequency oscillator embodying the invention;

Figure 2 is a front plan view of the oscillator, partly broken away to show a-portion of the control mechanism, taken .in the direction of arrows 2-2 in Figure 1;

Figure 3 is a vertical section taken on line 3-3 of Figure 1;

Figure 4 is another vertical section taken on line 4-4 of Figures 1 and 3;

Figure '5 is an enlarged detailed sectionof ,the Lecher wire capacitive short-circuiting member taken on line 5-5 of Figures land 3;

Figure 6 is a diagrammatic representation of the oscillator showing the electrical circuit; and

Figure 7 is a curve showing the tuning characteristics of the-oscillator ofFigure .1.

Referring to the drawings, the ultra-high frequency oscillator embodying my invention is entirely housed withina heavy, approximately rectangular, metal housing .2, preferably a onepiece aluminum casting of vfive sides having its sixth side closed by a heavy metal cover plate suitably secured thereto as by means of the screws 6. lhe upper left-hand corner of the rear of this housing is cut away at 8 to provide an aperture in which an oscillator tube H3 is mounted and through which it is connected to the other elements of the oscillator within the housing 2. An additional shi ld portion 52 of heavy metal, preferably an aluminum casting shaped as shown in Figures 1 and 3, is provided to surround. and shield the oscillator tube to and close the aperture 8, and is secured to th housing 2 by screws 54. This rugged, mechanically rigid housing 2, along with a variable lump capacity tuning element, hereinafter to be described, forms the primary frequency determining portion of the oscillator, and becaus of this rigid mechanical construction it imparts to the oscillator a high degree of frequency stability.

The vacuum tube It may be any suitable high vacuum tube capable, when connected in a properly designed circuit, of oscillating in the ultrahigh frequency range. The particular vacuum tube if shown in the drawings, is of the door knob type having three -elements-a plate, a control grid, and a filament-end is of th baseless variety in which the electrode supporting wires pass through glass seals in the envelope of the tube and act as the connector pins whereby the tube may be plugged into a suitable socket. In the present embodiment such a socket is formed by a right angle metal bracket or shelf i3 extending rearwardly from the back of the housing 2, as shown in Figures 1 and 3, and suitably secured thereto by screws and nuts IS. The central contact prong 29 of the tube In, which is one of the filament connections, passes through a close-fitting hole 22 in the bracket i and presses against a spring terminal member 24 soldered, or in some other suitable manner secured to the underside of bracket It to form a contact between the filament prong and the entire metal frame of the instrument, i. e., the housing 2. The other filament connection prong 25 passes through a large hole 28 in the bracket i6 and thence through a small close-fitting hole '36 in a metal plate 32 secured to the underside of bracket it by a suitable means such as the screws and nuts 33 but insulated therefrom by a strip of suitable low loss insulation material 34, such as that commonly known by the trade name Amphenol, and presses a spring contact member 35 soldered or in any other suitable manner secured to the metal plate 32. With this arrangement the plate 32 and the bracket 18 act as a condenser connected across the filament terminals 26 and 26 of the vacuum tube If to lay-pass any radio frequency currents which may appear on the filament terminal 26 to the terminal 20 which in turn is connected to what might be called ground, i. e., the housing 2 of the oscillator.

The plate connection prong 38 and the grid connection prong 4B of a vacuum tube it are inserted into two spiral spring connector members 42 and 44, respectively, which, in turn, are connected to the ends of two parallel brass rods l'd and A8, respectively, which act as a pair of Lecher wires to form with the vacuum tube to a long line resonant circuit which, when suitably connected and energized, forms an oscillator circuit of the type frequently referred to as a long line, transmission line, or 90 degree line oscillator. These rods 46 and 53 are so dimensioned that, including added length due to the effect of the elements of vacuum tube [8, they have an effective electrical length which is slightly greater than one-quarter of the longest wavelength to which it is desired to tune the oscillator. Inasmuch, however, as the elements of vacuum tubes have considerable influence in the ultra-high frequency or micro-wave spectrums, the total physical length of the rods 15 and is actually less than one-quarter of the longest wave-length. For example, in an actual oscillater of the construction shown in the drawings having a wave-length range of MA to 86.0 centi-- meters, the rods 46 and 58 were about four inches long although one-quarter of the longest wave length would be about 5.9 inches. The other ends of the rods so and "23 pass through and are rigidly secured to two supporting and guide blocks 53 and 52 formed of some suitable low loss insulation material, such as the above-mentioned transparent material commercially known by the trade name Amphencl. These insulated mounting blocks 50 and 52 are in turn secured by screws 54 to a rectangularly-shaped metal bracket 56 (see Figures 3 and 4) attached to the cover plate 4 of the housing 2 by means of screws 58, as shown in Figure 3. This structure holds the rods it and 43 rigidly in fixed relation to each other so that the spiral spring contact members 42 and 44 are properly positioned with respect to the holes 2?. and 3!! in the tube supporting bracket l6 so that they are always in proper position to make contact with the contact prongs 2%, 3S, and 49 of the tube i9 when cover plate d is secured to housing 2. As shown in Figure 4, two screws 60 and 62 are threaded through insulated blocks so and 52 and through the rods .5 and 48, respectively, to securely fasten the rods in the block 52 and to provide means for making electrical connections with the extremities of these rods. These rods t6 and 38 through screws to and 62 are connected by leads i5 3 and 38, respectively, to a pair of pin jacks E3 and i6 mounted on a metal cross member '52 extending between and secured to the upper sides it and "it (see Figure i) of the bracket 56, and insulated therefrom by insulation material l8. In a recess in the housing 2, immediately above the pin jacks 68 and iii, two metal sleeves 32 and B are secured by screws 8 i These sleeves partially shield and aid in the positioning of the pin-type plugs 86, shown only in Figure 4, used to connect the pin jacks '68 and E8 to external power circuits. Suitable capacities may be provided between the central pin members 88 of the plugs 85, if desired, thereby providing a lay-pass to the grounded housing 2 for any unwanted radio frequency currents which may appear on the leads 64 and E6.

Tuning of the long line oscillator circuit is accomplished by positioning of a radio frequency short-circuiting member, generally indicated at 99, along the Lecher wires and to effectively terminate or short the long lines as and 48 by determining the zero potential or nodal point on these lines. Details of construction of this short-circuiting member 916 are shown in the enlarged cross-sectional view in Figure 5. Essentially the shorting member is a condenser which, at ultra-high frequencies, offers a sufficiently low impedance to act as a suitable fleeting impedance at the nodal point of the Lecher wires. This condenser is formed of two flat plate-like members 92 and hav- -g tubular projections 95 and 28 formed on their outer surfaces and having their fiat faces separated by a strip of insulation material Etc. The tubular portions 96 and 98 snugly surround Leoher wire rods 46 and 48 so that the shorting member 80 may be slid alongthese rods todeterminethe frequencyof the "long line circuits thus formed. The plate-like members 92 and 84 are clamped together and secured to adriving'member I02 by screws I04. The screws *I04 are insulated from the members 92 and 94 and the driving member I02 by a sleeve of insulation material I06, and the driving member I02 is insulated from the plate member 92 by'an inter-layerof insulation material I08.

To tune the Lecher wires 46 and 48 by sliding the shorting member 50 therealong, as abovementioned, the driving member I02 is threaded to receive a partially threaded control shaft H 0 extending parallel to the Lec'her wires 46 and 48. This control shaft 110 is rotatably mounted in a bearing member II'2 attached by screws I I4 to the lower side of the insulated supporting block 50. A shaft IIB of insulation material, having a central recess H8 in one end thereof, is attached to the unthreadedend of the drive shaft III! by means of a screw I20, as shown in Figure 3. Theother end of this insulated shaft H6 is similarly secured by means of a screw I22 to one end of a gear shaft I24 which projects through the front cover plate 4 and is secured to a driving gear I26. Thus, the driving gear I26, rotated in a manner hereinafter to be described, rotates the threaded control shaft H0 to move the shorting bar 90 along the Lecher wires 45 and toward and away from the plate and grid terminals 38 and '40 of the vacuum tube I0, thereby to adjust the natural frequency of the long line circuit formed by the Lecher wires 46 and 48 and the shorting member 80.

A variable lumped capacity structure generally indicated at I30, is mounted within the housing 2 between the rear Wall thereof and the front cover plate 4. This variable capacity structure I30, in conjunction with the housing 2 and the cover plate 4, forms the principal frequency determining element of the oscillator from which the oscillator derives its 'high frequency stability. In the form shown in the embodiment of the invention herein described, this variable capacity element I30 comprises a plurality of concentric tubular members all having a common axis X-X extending from the back wall of the housing 2 to the cover plate 4. A first tubular member I32, provided witha flange portion I 34, is secured to the rear wall of a housing 2 by screws I35 passing through this flange portion. The end of the tubular member I32 is cut on a predetermined curve at an angle with respect to the axis X-X, as, for example, in the embodiment shown, along the oblique line I38, as shown in Figure 1. This predetermined contour on the end of the tubular member I32 permits the variable capacity structure I38 to be given any desired capacity variation curve, whereby, as will be hereinafter described, its operation may be synchronized with the operation of other elements of the apparatus,as, for example, with the tuning-of the Lecher wire structure by movement of the shorting member 50. Another cylindrical member I40,-of inside diameter equal to the outside diameter of tubular member I32 and of uniform length, is rigidly secured to the outer end'of member I32 asby means of a screw I42. On cover plate 4 opposite to members I32 and I40 and concentric therewith is mounted a third tubular member I 44 provided'witha flangeportion I46 whereby it is secured by means of screws I48 to the cover threaded control shaft a screw I58.

plate 4. asshown in Figure l. Tubular member I44 "has an inside diameter slightly less than the inside diameter of the opposing tubular member -I 32. A round piston-like plunger ISO is slidably mounted within the tubular .member I44 so as to be adapted to slide toward and away from the tubular members 132 and I to vary the electrical capacity between the plunger I50 and member I32. The capacity between capacity member 440 and plunger 150 does not change. This ring member I40 is provided to act as a lump capacity elementto determine the minimum lumped capacity of the resonance chamber and hence the highest frequency desired in the range of operation. "Thus, changing the dimensions of capacity ring member I 40 provides a:con venient method for determining the frequency range of the oscillator. The sliding motion of plunger I50 is obtained by means of a rotatable I52 meshed into athreaded axial hole I54 in the interior of the plunger I50. The threaded control shaft I52 is also threaded into one end of a collar I55 which in turn is secured to a gear shaft I56 by means of The gear shaft EI50 passes through a suitable bearing .hole in the cover plate 4 and is secured to an anti-backlash gear I60 by means of a set screw I62. A small pinion gear I64 is also attached to the outer end of shaft I56. A

30 long helical spring I66, surrounding control shaft 35 plunger I50 in response to I52 and collar I55, is compressed between the back of the front cover plate 4 and the end wall of a recess I03 in the interior end of the plunger I50 to prevent backlash in the motion of the rotation of control shaft I52. In order to prevent the plunger I50 from rotating within the tubular member I44, a slot I10 is out along side of the plunger I55 parallel to the axis X-X, as shown in Figures 1 and 40 4, and a stud I12 is threaded through the wall of tubular member I44 to engage the slot Il -0.

The oscillator is coupled to the external cir cuits with which it is to be used by means of a concentric cable, illustrated schematically at I13 in Figure 6, which is attached to a concentric cable coupling-device, generally indicated at I74, passing through one wall of the housing 2, as shown in Figure 1. This coupling member 114 comprises a threaded tubular sleeve I10 clamped in position in a hole in the wall of housing '2 by two threaded rings I18 and I80. A plug I82 of insulation material, such as the above-mentioned Amphenol, is secured in the center of the tubular member I16 and a resilient metal prong receptacle I84 is positioned in the center of the insulated plug I82. This metal prong receptacle I84 is connected by alead I86 to a tap I88 formed by a screw I90 threaded into the tu bular member I32 at some predetermined position. Additional taps for varying the coupling of the concentric line I13 with the oscillator may be provided by additional screws, such as I02. A standard concentric cable may be connected to this coupling member I74 in the usual manner.

Tuning of the oscillator shown throughout a wide frequency range is accomplished by simultaneously moving the short-circuiting member 90 along the Lecher wires 40 and 48 and moving the plunger I50 with respect to the fixed tubular members I32 and I40. The oscillator frequency increases as shorting member 50 moves toward Vacuum tube I0 and as plunger I50 moves away from the tubular member I32. This simultaneous movement of the shorting member 90 and the plunger IE0 is accomplished by providing the threaded control shafts I"! and I52 with right-hand threads and by meshing the operating gears I25 and IE9, connected respectively to the control shafts III] and I52, as shown in Figure 2, so that gear I26 turns in a counterclockwise direction when gear I65! turns in a clockwise direction. As above-mentioned, gear I63 is of the anti-backlash type, having two symmetrical gear members I60 and I94 so assembled that gear I 94 may rotate with respect to gear I60 which is firmly secured to gear shaft I55. Gear I94 is biased to rotate with respect to gear I60 by means of a tension spring I96, secured at one end to gear I60 and at the other to gear I94, so that the corresponding teeth in gears ISO and I94 tend to clamp the teeth of gear I26 under tension of spring I96, thus preventing backlash. The two gears I26 and IE9 are rotated simultaneously by a control knob IE8 attached to a shaft I99 journaled on the cover plate 4 and on a front panel 266 secured to th cover plate 4 by four screws 202 passing through four collars 224. The shaft I99 carries a pinion gear 206 which meshes with the antibacklash gear I66 as shown in Figure 2.

A calibrated dial 208, having gear teeth around its periphery, is mounted on a shaft ZIEl journaled in and extending between the cover plate 4 and the panel 2%. It is so positioned that its gear teeth mesh with the pinion Iiil mounted on the end of the gear shaft I56 attached to the variable capacity structure I38. A window-type aperture 2 I2 is provided in the panel 2% through which the calibrated dial 2H8 may be viewed. The dial 263 may be suitably calibrated so as to indicate the frequency of the oscillator as the control shafts It!) and 55. are rotated by rotation of the control knob 93 to vary the frequency of the oscillator circuit elements.

The electrical circuit of the oscillator is shown diagrammatically in Figure 6. The housing 2, including the cover plate i, is connected to ground. One filament terminal 28 of the vacuum tube It is connected to the housing 2, as abovedescribed, which in turn is connected through a lead 229 to one side of a suitable source of current (not shown) for heating the filament. The other filament terminal 26 is connected to the other side of the filament heating source through lead 222 and also to the metal plate 32 which forms a capacity with a portion of the housing 2 so as to by-pass to ground any radio-frequency currents which appear in the filament circuit. The grid connection ii) of the vacuum tube iii is connected to one end of rod 18, as above-described. The other end of rod 43 is connected, through the lead 66 and the pin pack ill, to a variable grid bias resistor 224, the other side of which resistor is connected through a suitable grid current meter 225 to ground. The plate connector 38 of vacuum tube Ill is connected to one end of the other Lecher wire or rod Mi and the other end of this rod is connected, through lead 64 and pin jack 6%, to the positive terminal 228 of a source of high D. C. potential, not shown, the negative terminal of which is connected to ground. A suitable high potential A. C. might be used in place of D. 0., if desired. As abovementioned, suitabl capacities may be provided at the pin jacks t8 and w, by which the plate and grid leads pass through the housing 2, so as to provide a bypass to ground for any unwanted high frequency currents which may appear on these leads beyond the shorting member 90. Thus, the portion of the rods 46 and 48 between the plate and grid of the vacuum tube I6 and the shorting condenser 86 act as Lecher wires, i. e., as a long line resonant circuit, to generally set the frequency of oscillation of the oscillator circuit, and the portion of these rods beyond the shorting condenser 99 merely act as connections to the plate supply 228, and to ground through the grid resistance 224. The long line oscillator thus formed is completely shielded by the housing 2 and the cover plate 4, and it is coupled to an ultra-high frequency resonator structur formed by housing 2, cover plate 4, and the variable lumped capacity structure iii This latter structure, as above-described, forms the primary frequency-determining element of the entire oscillator and, being very rigid mechanically, one which has a degree of frequency stability comparable with that obtainable with a piezo-electric crystal. However, it has the decided advantage over a crystal-frequency control arrangement that, due to the provision of the variably positioned plunger I59, the fundamental resonance frequency of this resonator may be readily varied through a wide range of frequencies without materially altering its stability or efficiency.

As above-mentioned, the oscillator is coupled to external circuits with which it is to function through a concentric line H3, the outside shell of which is connected to the housing 2 through the threaded portion I16 of the coupling member I14 and the inter-conductor of which is connected through the receptacle I84 to a tap I88 on the tubular member I32 of the variable capacity element I353. The position of this tap may be varied to vary the coupling of the oscillator with external circuits. If desired, this coupling may be accomplished inductively by means of a loop or capacitively by means of a coupling plate instead of by means of the tap provided in the embodiment described. In this connection it should be noted that the smaller the coupling to outside circuits through concentric cable I13, the greater will be the stability of the oscillator, and

, by the same token, the smaller will be the power output of the oscillator. Thus, the amount of coupling to be used must be determined by the use to be made of the oscillator. The connection shown in Figures 1 and 6, in which the center conductor of cable I73 is connected to tap I88, provides fairly tight coupling to external circuits; whereas a connection to tap I92, or coupling by means of a capacity plate or an inductive loop would provide a considerably looser connection to external circuits and therefore greater frequency stability.

By means of the gear structure shown in Figure 2, with proper choice of the pitch of the threaded control shafts Iii) and IE2; size of the gears I23 and I68; dimensions of the Lecher wires it and 48, of the housing 2 and cover plate 4,

of the variable capacity element I39; and shape of the curve I38 of the tubular element I32 of this structure, the movement of the shorting member 90 and the variable capacity plunger I50 may be so synchronized that the oscillator will oscillate with high frequency stability throughout a wide frequency range. This is illustrated by the curve shown in Figure '7, which is the tuning curve of such an oscillator in actual operation, showing the straight-line relationship between the position of the shorting condenser member 96, the position of the capacity plunger 1I511, and the oscillator wave-length in centimeers.

Thus, with an, oscillator of the type described embodying my invention, ultra-high frequency oscillations of great stability can be generated without difficulty, even above 1000 megacycles, and the frequency of these oscillations can be varied at will throughout a widerange by simply turning the single control knob I98. Thus, the delicate adjustments throughlong control shafts and the need for tuning thefilament circuit and other potential supply circuits, so necessary in oscillators of, previously known types, are eliminated.

As many embodiments may be made in the above invention and as many changes may be made in the embodiment above'described, it' is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative only and not in alimitingsense.

I claim:

1. A stable self-shielded, ultra-high frequency, high-capacity resonant circuit, comprising, in combination, a closed metal container, a first tubular metal member secured at one end to one wall of saidccntainer with, its free end projecting inwardly therefrom, a second tubular metal member secured at one end to the approximately opposite wall of said container with its free end projecting inwardly therefrom toward and concentric with said first tubular member to form therewith an electrical capacity, at least one of said two tubular members being extensible to permit relative movement between the adjacent free end portions thereof, a third tubular metalmember secured near-the free end of said second tubular member and concentric with said first tubular member to form with said first member a fixed lumped electrical capacity, means for predeterminedly changing the resonance frequency of the high-capacity resonant circuit thus formed by said container and said three tubular members comprising means for relatively moving the free ends of said first and second members with respect to each other along their common longitudinal axis while maintaining a fixed electrical capacity between said third member and said first member, and coupling means positioned within said container for connecting said resonant circuit to an external electrical circuit.

2. A stable self-shielded, ultra-high frequency, high-capacity resonant circuit, comprising, in combination, a closed metal container, a first tubular metal member secured at one end to one wall of said container with it free end projecting inwardly therefrom, a second tubular metal member secured at one end to the approximately opposite wall of said container with its free end projecting inwardly therefrom toward and concentric with said first tubular member to form therewith an electrical capacity, the free end of one of said members being shaped to terminate in a plane oblique to the common axis of said members, at least one of said two tubular members being extensible to permit relative movement between the adjacent free end portions thereof, a third tubular metal member secured near the free end of said second tubular memher and concentric with said first tubular member to form with said first member a fixed lumped electrical capacity, means for changing the resonance frequency of the high-capacity resonant circuit thus formed by said container and said three tubular members in a manner predetermined by the angle between said plane and said common axis comprising means for relatively moving the free ends of said first and second members with respect to each other along their common longitudinal axis while maintaining a fixed electrical capacity between said third memberand said first member, and coupling means positioned within said container for connecting saidresonant circuit to an external electrical circuit.

3. A stable self-shielded ultrahigh frequency oscillation generator, comprising, in combination, a closed metal container, a tubular metal member secured atone end to one wall of said container with itsfree end projecting inwardly therefrom, an extensible cylindrical 'metal member secured at one end to the approximately opposite wall concentrically with said tubular member with its me end projecting inwardly toward but out of physical contact with said tubular member to form an electrical capacity therebetween, a threadedshaft meshed into a threaded hole along the longitudinal axis of'said cylindrical member near the free end thereof, first control means for rotating said shaft to move the free end of said cylindrical member into and out of said tubular member to vary the resonance frequency of the resonator formed by said container and saidconcentric members, a transmission line electron tube oscillation generator positioned within said container andcoupled to said resonator to form a stable oscillation producing unit, second control means for tuning said generator, manually operable means mounted on the outside of said container and operatively connected to said first and second control means for simultaneously operating said control means to determine the oscillation frequency of the oscillation producing unit formed by said generator and said resonator, and coupling means positioned within said container for connecting said resonator to an externalelectrical circuit to be energized by said oscillation producing unit.

4. A source of ultra-high frequency oscillation, comprising, in combination, an ultra-high frequency resonator chamber, an electron tube mounted in said chamber, a ninety-degree transmission line connected to said electron tube and completely contained in said chamber to form a transmission line oscillator, and coupling means coupled to said resonator for connecting said oscillator combined with said resonator to external electrical circuits as a source of oscillation.

5'. In combination, an electron oscillator tube, a long-line oscillator circuit operatively connected to said tube, a metal housing enclosing said tube and circuit, said housing acting simultaneously as an element of a tuned circuit determining the oscillation frequency of said oscillator and to completely shield said oscillator.

6. An ultra-high frequency oscillation generator, comprising, in combination, a completely closed metal container, a metal projection extending inwardly from one wall of said container toward a portion of an approximately opposite wall thereof and forming an electrical capacity therebetween, first control means connected to said container to vary the distance between the end of said projection and said opposite Wall portion, an electron tube mounted in said container, a pair of approximately parallel conductors directly connected to the elements of said tube and extending across the interior of said container to form with said tube a long-line ultra-high frequency oscillator circuit, a bridging member electrically connecting said parallel conductors at any desired point along their length, second control means associated with said bridging member to vary its longitudinal position along said conductors, and operating means mounted on the outside of said container and connected with said first and second control means to simultaneously operate said control means to determine the oscillation frequency of said generator.

'7. An ultra-high frequency oscillation generator, comprising, in combination, a completely closed metal container, a metal projection extending inwardly from one wall of said container toward a portion of an approximately opposite wall thereof and forming an electrical capacity therebetween, first control means connected to said container to vary the distance between the end of said projection. and said opposite wall portion, an electron tube mounted in said container, a pair of approximately parallel conductors directly connected to the elements of said tube and extending across the interior of said container approximately parallel to the axis of said metal projection to form with said tube a long-line ultra-high frequency oscillator circuit, a bridging member electrically connecting said parallel conductors at any desired point along their length, second control means associated with said bridging member to vary its longitudinal position along said conductors, and operating means mounted on the outside of said container and connected with said first and second control means to simultaneously operate said control means to determine the oscillation frequency of said generator.

8. An ultra-high frequency oscillation generator, comprising, in combination, an electrical resonator comprising a metal container and an extensible metal projection connected to one wall of said container and extending across the interior thereof toward an approximately opposite wall portion, means for varying the extension of said projection toward and away from said wall portion to determine the resonance frequency of said resonator, a long-line type ultrahigh frequency oscillator circuit including a vacuum tube mounted within said resonator, and means extending into said resonator for coupling said oscillator through said resonator to external electric circuits.

9. An ultra-hi h frequency oscillation generator, comprising, in combination, an electrical resonator comprising a metal container and an extensible metal projection connected to one wall of said container and extending across the interior thereof toward an approximately opposite wall portion; means for varying the extension of said projection toward and away from said wall portion to determine the resonance frequency of said resonator; a long-line type ultra-high frequency oscillator circuit mounted within said resonator and including a pair of parallel conductors, a capacitive element to bridge said conductors to determine the resonance frequency thereof, and a three-element vacuum tube having a grid connected to one of said conductors, an anode connected the other of said conductors and a cathode connected to said metal container;

and means extending into said resonator for coupling said oscillator throu h said resonator to external electric circuits.

10.An ultra-high frequency oscillation generator, comprising, in combination, an electrical resonator comprising a metal container and an extensible metal projection connected to one wall of said container and extending across the interior thereof toward an approximately opposite wall portion; first positioning means for varying the extension of said projection toward and away from said wall portion to determine the resonance frequency of said resonator; a long-line type ultra-high frequency oscillator circuit mounted within said resonator and including a pair of parallel conductors, a capacitive element to bridge said conductors and a three-element vacuum tube having a grid connected to one of said conductors, an anode connected to the other of said conductors, and a cathode connected to said metal container; second positioning means for moving said capacitive element to any predetermined point along said conductors; means extending into said resonator for coupling said oscillator through said resonator to external electric circuits; and frequency control means for simultaneously operating said first and second positioning means to determine the oscillation frequency of said oscillator.

11. A stable ultra-high frequency oscillation generator, comprising, in combination, an ultrahigh frequency resonator chamber, means positioned therein for determining the resonance frequency of said chamber, an oscillator tube, electric resonant circuit means connected to said oscillator tube to form therewith a complete ultra-high frequency oscillator circuit, said resonant circuit means determining the oscillation frequency of said oscillator circuit, mounting means in said chamber for said oscillator tube and said resonant circuit means to position the oscillator formed thereby in electrically coupled relationship with said ultra-high frequency resonator, and means extending into said resonator chamber for coupling said resonator to external electric circuits.

12. A. stable ultra-high frequency oscillation generator, comprising, in combination, an ultrahigh frequency resonator chamber, first adjustable means positioned therein for determining the resonance frequency of said chamber, an oscillator tube, second adjustable electric resonant circuit means connected to said oscillator tube to form therewith a complete ultra-high frequency oscillator circuit, said resonant circuit means determining the oscillation frequency of said oscillator circuit, mounting means in said chamber for said oscillator tube and said resonant circuit means to position the oscillator formed thereby in electrically coupled relationship with said ultra-high frequency resonator, means extending into said resonator chamber for coupling said resonator to external electric circuits, and control means external to said chamber connected to said first and second adjustable means to adjust them simultaneously to tune said resonator and said oscillator circuit to substantially the same frequency.

STEPHEN D. LAVOIE. 

